Potion of holy water

A potion of holy water (unidentified, a "blessed clear potion" if BUC is known) is the blessed version of a potion of water. You can use it with the #dip command to remove curses or bless objects. Objects dipped into a potion of holy water do not become wet.

Dip a blessed object into holy water, and you get message "Interesting..."; the potion is not consumed. A useful way to verify that a certain potion is blessed before quaffing it (for example).

NetHack provides a few other ways to remove curse, but holy water is the main way to provide the "blessed" status to objects.

Quaffing a potion of holy water cures lycanthropy and, for non-chaotics, cures all illnesses. It does damage to chaotics. Holy water can be thrown at (or wielded against) demons, undead, and lycanthropes to cause 2d6 damage (i.e. more than early-game weapons, but normally not by enough to matter). However, most of the time holy water is used for blessing objects.

Obtaining holy water

Starting with it

A Priest(ess) starts with 4 potions of holy water, and a Wizard sometimes starts with holy water.

Dipping water into holy water

Once you have some holy water, you can easily #dip uncursed potions of water into the holy water. The entire stack of uncursed water will become holy water, and you will only lose the one potion of holy water.

Before doing this, make sure the potions of uncursed water are stacked in your inventory. If they are not (for example, if you were diluting them), then use the extended command #adjust to adjust all of those potions to a single inventory slot -- this will make them stack onto that slot (alternatively, drop all the scattered waters and pick them back up, which is faster but consumes two in-game turns).

Note that using that method with unholy water will only change it to uncursed water, so you will need to use two potions of holy water to turn a stack of unholy water into a stack of holy water. However, unholy water does have some uses, so it might be beneficial to keep it.

Provided that you can #pray safely, all of the water dropped on the altar should become holy water; you can test this by taking the water and dropping it again to check for the flash.

Note that you will still get the regular results of prayer in addition to making the water holy.

Confused remove curse

For example, if you are carrying 10 non-stacked uncursed potions of water, reading a blessed scroll of remove curse while being confused gives you a 94.3% chance of holy water. You might want to unequip any uncursed armor, weapon, jewelry, or leashes first.

Reading a blessed scroll of remove curse while being confused has a 25% chance of blessing, 25% cursing, and 50% leaving alone each uncursed item in your main inventory, and an uncursed one affects uncursed wielded (or in-use) items.

If you have a magic marker, but none of your scrolls of remove curse are blessed, you can blank any other blessed scroll and write remove curse.

Shops

Sometimes a potion of holy water will be randomly generated. In particular, an expensive potion of water in a shop must be either holy or unholy. If your pet steals it or moves over it non-reluctantly, it's holy. Shops sell holy water in 14.4% of all dungeons.

Blessed horn of plenty

A horn of plenty will sometimes produce potions. If the horn is blessed, any clear potions it produces will be holy water. However, horns generated on the floor of newly-visited levels are always uncursed. If you can bless a horn, you can usually make holy water directly.

Conduct considerations

Polymorphblessedpotions (e. g. from throne farming) (to accomplish this without breaking any other conducts, identify blessed potions by comparing the sizes of your potion stacks and making use of the fact that uncursed potions are 6 times as likely as blessed ones.)

This is an exhaustive list of ways to make holy water. 53% of all games randomly generate holy water in the mines or the main dungeons down to Medusa's Island. Water made by dilution, cancellation, unicorn horn, or alchemy is always uncursed. Randomly generated horns of plenty are always generated uncursed, too.

Holy water conservation

Any number of stackable items can be dipped into one potion of holy water. So, if you have, say, 12 scrolls of identify that you want to bless, but they are scattered across various inventory slots because some are cursed, some are uncursed, some are of unknown status, and so forth, you will save holy water by first B/U/C testing them all at an altar, which will cut your number of stacks down to two. Then, dip all the cursed items in one potion, and you will have a single stack of uncursed items. Dip all of them in a second potion, and they will all be blessed.

When you are manipulating items in this fashion, you may need to un-#name items or use the #adjust command to force NetHack to merge identical items into a single inventory slot, or drop the items and pick them up again.

Strategy

From the mid-game on, it is a good idea to leave a potion of holy water openly on the floor of some level you can quickly level- or branch-port to. In case you do accidentally wield a cursed two-handed weapon, you'll have a hard time retrieving it from your bag.

Which items deserve blessing the most depends heavily on the player, but there are certain items that are great targets for blessing because of the advantage it confers:

A blessed bag of holding will cause items within to weigh a quarter as much, as opposed to half as much in an uncursed bag; this confers a great advantage in how much you can carry, lifting off upwards of 200 units of weight off your back.

A blessed potion of gain level advances your level and puts you part way to the next level, while an uncursed one only advances you to the bottom of the next level. Early on, this can be quite useful. Later, the XP requirements for advancing a level become so steep it doesn't help much, as advancing a level naturally would still require considerable farming.

A blessed scroll of genocide will wipe out an entire monster class as opposed to only one species. The more monsters in the class, and the more dangerous they are, the better; Liches are an especially common target.

A blessed scroll of charging always gives a recharged item its maximum number of uses. This is most useful for saving a "2 blessed scrolls of charging" wish from a wand of wishing, allowing you to use it on something more useful.

If you use ranged weapons, which have a chance of disappearing, blessing them drastically lowers the chances they will do so.

SLASH'EM

The Potion of amnesia can be dipped into any water source, diluting it into a potion of water immediately. Unlike normal dipping, this does not change the beautitude, and can be used to create (un)holy water. Potions of amnesia can have some other useful uses however.

Some shops offer an "uncursing service", at 150 zorkmids (+various modifiers). If you are hallucinating, there is a 1/4 chance the shopkeeper will be distracted and accidentally bless the item.

If you want to create holy water with a shops service, you should first get a good deal of credit with the shopkeeper. Then engrave or burn Elbereth, to avoid accidents. And of course, having a unicorn horn to cure the hallucination in the end.

Don't forget that hallucination is SLASH'EM also messes up your inventory. So don't forget the inventory letter for your potion of water.

Encyclopedia entry

"We want a word with you," said Ligur (in a tone of voice
intended to imply that "word" was synonymous with "horrifically
painful eternity"), and the squat demon pushed open the office
door.
The bucket teetered, then fell neatly on Ligur's head.
Drop a lump of sodium in water. Watch it flame and burn and
spin around crazily, flaring and sputtering. This was like
that, just nastier.
The demon peeled and flared and flickered. Oily brown smoke
oozed from it, and it screamed and it screamed and it screamed.
Then it crumpled, folded in on itself, and what was left lay
glistening on the burnt and blackened circle of carpet, looking
like a handful of mashed slugs.
"Hi," said Crowley to Hastur, who had been walking behind Ligur,
and had unfortunately not been so much as splashed.
There are some things that are unthinkable; there are some
depths that not even demons would believe other demons would
stoop to.
". . . Holy water. You bastard," said Hastur. "You complete
_bastard_. He hadn't never done nothing to _you_."
"Yet," corrected Crowley.